GB1267298A - Improvements in or relating to processes for making bulked yarns by the fibrillation of thermoplstic films - Google Patents

Abstract

1,267,298. Fibrillating films. HERCULES Inc. 29 April, 1970 [6 May, 1969], No. 20709/70. Heading B5B. A process for forming continuous filaments by fibrillating a film and simultaneously bulking the filaments involves feeding a ribbon of longitudinally oriented thermoplastic film having longitudinal parallel striations (Fig. 3) at a predetermined speed, surrounding the ribbon with a jet of fluid at a temperature sufficient to plasticize the ribbon without loss of orientation and directing the fluid jet, and thus the ribbon, into a bulking chamber having an open end opposed to the fluid jet and a cross-sectional area sufficient to permit limited lateral movement of the fluid jet. A screen is moved laterally across and in close proximity to the open end of the chamber at a substantially slower speed than the speed at which the ribbon is fed into the chamber and by thus confining the fluid jet to exhaust through the screen randomly deflects the jet and hence the ribbon laterally within the chamber at a rapid rate and thereby fibrillates the film. The resulting filaments are folded on to the screen and are randomly crimped as they are moved out of the chamber by being compressed against the surface of the screen. Suitable apparatus for the process of the invention is that of U.S. Patent 3,457,611, Figs. 1 (not shown), and 2 in which striated ribbon R is fed through yarn-tube 15 and urged into bulking chamber 14 by a fluid jet, which may be steam under pressure, supplied to capillary tube 13 by way of channels 12, chamber 29 and supply pipe 30, 31. The ribbon is substantially completely fibrillated in chamber 14 by random rapid lateral movement induced by deflection of the jet, and thus the ribbon, from areas of the slowly moving screen 3 which are densely covered with fibrillated filaments to areas which are less densely covered. The filaments then pass under the lower surface 35 of the jet unit 2 and are randomly crimped by the pressure of the jet unit on the screen 3. Suitable striated film for use in the invention is that of Fig. 3 which is fibrillated to form continuous filaments of specific cross-section, Fig. 4 (not shown). In an example a ribbon of polypropylene of the above cross-section is fibrillated and crimped using the above apparatus.